Sewing machine stop motion



Feb. 9, 1965 Filed Oct. 51, 1961 J. F. MORIN 3,

SEWING MACHINE STOP MOTION 2 Sheets-Sheet l 11 f i: f i 1; i if fiu i/w Feb. 9, 1965 .1. F. MORIN 3,163,831

SEWING MACHINE STOP MOTION Filed Oct. 51, 1961 2 Sheets-Sheet 2 United States Patent 3,168,881 SEWING MACHINE STOP MOTION Joseph F. Morin, Westwood, Mass., assignor to The Wiiliam Carter Company, Needham Heights, Mass, a corporation of Massachusetts Filed Oct. 31, 1961, Ser. No. 149,095 Claims. (Cl. 112-219) highly sensitive and at the same time reliable thread stop motion for the needle thread in a high speed sewing machine, which can be depended upon to stop the machine at once upon the failure of the sewing mechanism to form and draw ina stitch.

In accordance with this object of the invention, the

thread stop motion is applied to a portion of the needle thread adjacent a point where it passes through the eye of the rapidly reciprocating needle. In the illustrated construction the needle thread guiding means includes a thread take-up and a thread guide at the needle side of the take-up located to provide 'a substantially vertical run of the needle thread downwardly from said thread guide to the needle. A horizontally disposed detector arm pivoted on the machine is formed with a thread guide which engages and deflects an intermediate portion of said vertical run of thread, whereby each repeated tightening of said vertical run of thread in each successive stitch drives said detector arm and thread guide thereon from below upwardly toward a position providing substantially equal lengths of said thread at each side of said thread guide. The arrangement of detector arm to thread run shown in whichthe thread guide mo ves-along' a path substantially parallel to the general direction of 'travel of the thread producing a varying bend therein has the advantage that only a relatively small amount of come and go ,in the thread isrequired to produce a substantial signal movement of; the; detector arm. It is an essential element of my improved thread stop mo tion that the detector arm is held in its intermediate machine runningposition, by the rapidly recurring tightenings of the thread. Any tendency which might exist for the thread arm to oscillate appreciably following the suc- 3,168,881 Patented Feb. 9, 1965 the first stritch or two are completed. Under these circumstances the highly sensitive needle thread stop motion of the present invention, if allowed to operate at this time, would instantly arrest the automatic operation of the machine.

It is a further object of the invention to provide a needle thread break stop device which is well adapted for usein a high speed intermittent operation sewing machine to insure the instant stopping of the machine upon loss of tension upon the needle thread, and which will at the same time prevent activation of the thread break stop device preceding and during the sewing of the initial and final stitches of each succeeding group.

It is a further object of the invention to provide in combination with the highly sensitive tension arm con trol herein described a means for rendering the stop motion inoperative at a predetermined position of the machine with relation to any automatic cycle of operations the machine is called upon to perform, so that a high degree of certainty and ease of operation is maintained in the operation of the machine.

The several features of the invention together with the advantages to be obtained thereby will be evident from the following de cription taken in connection with the accompanying drawings, in which:

FIG. 1 is a somewhat fragmentary view of an automatic high speed chain stitch sewing machine embodying in a preferred form the several features of the invention;

FIG. 2 is a view in right side elevation of substantially the parts shown in FIG. 1;

FIG. 3 is a perspective view of the tape showing a line of stitches inserted during a sewing cycle of the machine;

FIG; 4 is a diagram of the electrical thread break machine stop circuit; I

FIG. 5 is a somewhat diagrammatic view of the automatic sewing machine shown in FIGS. 1 to 4 but illustrating a modified form of my thread break stop device;

FIG. 6 is a view in right side elevation of substantially the parts shown in FIG. 5; and

FIG. 7 is a diagram of the electrical thread break machine stop circuit associated with the modified thread stop motion of FIGS. 5 and 6.

' 'The' automatic chain stitch sewing machine shown in cessive rapid fluctuations of the tension .between m a'ximum and zero values is effectively damped out by the weight and consequent inertia of the arm. While in the embodiment shown the detector armv and associated said switch. a g g In the automatic sewingmachine shown a further difficulty is encountered because of the .loss of thread tenion' which accompanieseachstarting and stopping of the sewing mechanism'betweensuccessive group stitching operations. At thestart ofa new series of stitches when. the thread end is not 'yet firmly anchored by the fabric,

the normal running tension lever is not attained until vention comprises a machine base 20, anda sewinghead 22, these. parts providing support for'the usual sewing and work. feeding devices including a vertically disposed eye pointed needle 24, a looper 26, a presser foot 28 and a thread take-up 30. The tape is moved laterally with relation to the sewing mechanism on a cross slide 32, and is fed longitudinally through the machine by means of an intermittently driven feed roller 34. At the end of each seam thethread is cut beneath the work by means of a thread cutting hook 36. I

The needle 24 is mounted for vertical reciprocatory movements with a needle bar 38 in a housing 40 mounted for forward and back rocking movements on a pivot 42. The needle 24 and take-up 30 are driven by means of a rocker arm 44 which is pivoted at 46 on the machine head and is given an oscillatory movement by means of a verticaldriving link 48 from mechanism in the base (not shown); The needle bar-38 is connected for vertical movement to a forward extension 50 of the rocker arm 44,

the extreme forward end of which forms the take-up 30.,

movement by means of a link :72. The thread severing 1 hook 36 is a sliding member which is connected by a link 58 with a rearwardly extending rock shaft 6% actuated by mechanism not here shown.

The thread drawn from supply passes around a friction guide 62, roller 64 and guide 66 to a pull-off hook 68, then through a thread guide "iii formed in the takeup 30 and through the eye of needle 24. to the work. The pull-off hook 68 is actuated by a connection (not shown) so that a length of thread is drawn cit at the end of each sewing operation.

My improved thread break detector and stop motion device which forms more specifically the subject matter of the present invention comprises a horizontally disposed thread engaging detector arm 74 pivoted at 76 to a bracket 73 on the base 20, and is arranged to act against a portion of the feeding needle thread immediately above the eye of the reciprocating needle. The vertical run of the thread above the needle eye is deflected at a small angle by engagement with a thread engaging pin 8%} on the arm '74 around which a portion of the thread extending between the thread guide 70 formed in the thread take-up 3t and needle 24 is bent. The detector arm is weighted'so that the arm and pin 8% are biased in a downward direction. During normal operation of the sewing machine thetension on that portion of the thread immediately adjacent the needle shifts rapidly from zero to a maximum value with each reciprocation of the needle, so that repeated jerks are given to the detector arm as the thread is drawn in by the thread takeup 30 in the formation of each successive stitch. The detector arm is thus nudged upwardly and caused to ride approximately in the position shown in FIG. 2.

The wide fluctuations in tension and extensive come and go of the thread with each needle reciprocation are successfully damped out and the relative light nudging effect is provided by means of the arrangement in which a weighted detector arm having a substantial amount of inertia is caused to form a transversely extending indent in a run of thread to the needle extending in an up and down direction; Each increase of tension tends to equal i ze the length of the two legsof the indent thus nudging thereto would also move laterally in the general direction of said thread system'against a bias in one direction provided bya spring or similar device not here specifically shown. 7

Any sustained loss of thread tension causes thedetector arm 74 to drop counter-clockwise into engagement .with "the operating pin 82 of a micro-switchii i The ment of the thread engaging detector arm to the machine stop position. 7

in the embodiment of the invention shown in FIGS. 1 to 4 or" the drawings, the stop motion control device is shown as comprising a control member 8-6 which is rigidly secured to and projects downwardly from one of the tape guide bars which form part of the cross slide 32 into engagement with the cammed upper surface of a switch actuating arm 88 pivoted at hit on the machine base 20. The actuating arm 38 is normally held in the raised position shown in MG. 2 by means of a small tion as the slide moves during the sewing of the first stitches of the series. Thereafter the control member rides onto the raised surface of the actuating arm 88 thread engaging detector arm '74 and micro-switch 84. 7

provide a thread tension sensitive detector device which. is efiective to detect loss of tension which might be caused, for example, by breakage .or exhaustion of the It. will be understood that the stop feeding thread. position of said detectorarm and corresponding bias thereon may be up instead of down if so desired.

A further element of the improved detector and stop motion device of the present inventioncomprises means which willoperate in timed relation with the: operation of the automatic machine described to render the needle thread actuated stop device inoperative at predetermined points in the automatic cycle which will thereby positively prevent the inadvertent operation of the stop motion during successive pauses in the operation of the sewing to depress the arm %8 and close the switch $6.

As best shown in FIG. 4 the micro-switches 84 and are connected in series in a machine stop motion circuit which also includes the sewing machine clutch sole- 7 noid 1%. v V V v The operation of my improved needle thread break eteetor device as applied to a fully automatic intermittent operation sewing machine in the embodiment shown in FIGS. 1 to 4 inclusive will be briefly described as follows:

The automatic sewing machine illustrated operates in accordance with an automatic cycle in which a tape is advanced a metered length and positioned with relation to a cross slide. Stitching'then commences, the slide being moved to cause the stitching to progress transversely across the tape and then back to the initial starting position. At this point the stitching ceases and the tape is again advanced causing thesewn portion of the tape to be moved out of the way. This operation is then repeated so that successive portions of the tape are sewn in rapid succession.

Each time the'sewing machine starts in operation, the

tension on the needle thread builds up, successive tightening of the thread extending upwardly from the needle eye as each successive stitch is formed providinga series 7 ofimpulses causing the detector arm to be nudged upwardly to the intermittent operating position shown in FIGS. 2 and 4. During the initial starting period in which the arm 74 may not have been raised enough to' open micro-switch 84, the control member 8% carried on the cross slide 32 'is engaged with the low portion of the cam upper surface of actuating arm .88 which remains raised thereby holding switch 96 open: By the time the control member 86 rides on the surface of actuating arm 88 closing switch 96, the switch 84'will have opened and a the stop motion device cuit setting.

is then in normal operating cir- In this embodiriientyof the invention, additional provision is made for rendering the stop motion inoperative at the further endof thestitching operation inwhich an I inadvertent continuation of the line of stitchingbeyond the edge of the tape might otherwise cause the stop rnotion to function. To this end, control member 86 is caused againto ride on a, low portion of the actuating arm 88, thus causing'micro-switch 96 to be held open.

In the-event, however, ofia breakage; of thread or u on sustained loss of thread tension iorariy other reason during the stitching of the principal portion of the scam, the closing-of switch 84 will cause clutch solenoid 198 to I be energizedto stop the machine. i

FIGS. 5 to 7 inclusive of the drawingsillustrate a modified form of my" improved thread break stop mechanism in which a mechanically operating device is substituted for the actuating arm 88 and the second micro-switch 96 to render the thread stop motion inoperative at the beginning and end of each successive cross stitch forming cycle.

The thread passing downwardly to the eye of the reciprocating needle 24 is engaged by a pin 104 mounted on a thread engaging detector arm 106 pivotally supported on a pivot pin 168 on a fixed bracket 110 depending from the sewing head 22. The middle portion of the thread engaging detector arm 106 is jogged or sloped so that the rearward end of the arm is at a higher level than the forward thread engaging end portion. The arm is balanced so that the thread engaging end thereof, if un supported, tends to move downward.

Toward its rear end the arm 106 is provided with a contact element 112 which is adapted for engagement with a micro-Switch 114 carried by the bracket 110, said parts being arranged to effect such engagement whenever the switch arm is permitted to rock in a counter-clockwise direction.

The thread engaging detector arm 106 above described is adapted to operate in the same manner as the arm 74 above described, being arranged whenever the thread tension becomes insufiicient to rock counter-clockwise and thereby to engage said micro-switch 114.

In this embodiment of the invention a mechanical device is provided for preventing movement of the detector arm 19rd in a counter-clockwise direction to its stop position during the sewing of the initial stitches and the final return stitches during the sewing of each successive cross and return stitch group. The device referred to comprises a post 116 extending upwardly from the cross slide 32, having mounted thereon a transverse arm 118 adjustably secured to the post by a set screw 12%. For the initial and final stitches of each seam the slide 32 and control arm 118 are located so that the arm 1118 engages and positively limits movement of the detector arm 1% and said counter-clockwise direction.

In the operation of the modified construction shown in FIGS. through 7, the clutch solenoid actuating coil will normally be inactivated by the open switch 114. In the event that the thread engaging detector arm 166 is permitted to drop by failure of the thread tension after the machine is started and after the cross slide 32 and transverse control arm 118 have moved a sufiicient distance, the arm 106 is permitted to drop in a counterclockwise direction to close the micro-switch and thereby to energize the clutch solenoid referred to.

The invention has been described and illustrated in connection with an automated sewing operation in which the seam is formed over and back across the work without interruption so that there is only one starting position, and as set forth in the embodiment of FIGS. 1 to 4 inclusive, at the opposite end of the run one reversing position for which provision must be made to render the stop motion inoperative. It is contemplated that other stitch forming patterns may be employed in connection with which the stop motion must be rendered inoperative for positions other than the initial starting position and reversing position above referred to. Provision for rendering the stop motion inoperative for any desired relative position of the sewing mechanism and work support is readily achieved by a suitable correction in the cam and follower connections for rendering the stop motion inoperative. With respect to the first embodiment of the invention shown in FIGS. 1 to 4 inclusive this can be accomplished by a suitable contouring of the activating arm 88. In the second embodiment of the invention the desired control of the detector arm 1% is achieved by a provision of one or more control members which can be positioned to prevent movement of the detector arm 1G6 to the stop motion actuating position for any said relative position of the sewing mechanism and work support.

It will be understood that the thread stop motion of the present invention is not limited in its application to the particular type of machine shown, but is equally applicable to other types of machines having reciprocating thread carrying needles including high speed lock stitch sewing machines which may be adapted for automatic intermittent operation, to provide for the instant stopping of the machine in the event of a loss of tension on a thread passing through the eye of the reciprocating needle.

The invention having been described what is claimed is:

l. A sewing machine stop motion for use in a high speed sewing machine having sewing mechanism including a reciprocating eye-pointed needle operative in highspeed repetitive cycles, and thread guiding means including a thread take-up having a thread guide located to provide a direct run of the needle thread from said thread guide passing through the needle eye to the work, which comprises a detector arm pivotally mounted on said machine to move generally in the direction of said run, a thread engaging element on said detector arm engaging and deflectirn an intermediate portion of said run to form a transverse indent in said thread with the two legs thereof terminating respectively in said needle eye and in said thread guide, said arm being biased in a direction to urge said thread engaging element toward one end of said run, whereby the intermittent tightening of said run of thread in high-speed repetition with each needle reciprocation nudges said thread engaging element and detector arm to an intermediate running position tending toward that in which the legs of said indent are of equal length, and a machine stop device arranged to be actuated by the biased movement of said detector arm and thread engaging element toward one end or said run from said machine running position.

2. A sewing machine stop motion for use in a high speed sewing machine having driving mechanism including a reciprocating eye-pointed needle operative in highspeed repetitive cycles, and thread guiding means including a thread take-up having a thread guide located to provide a direct run of the needle thread from said thread guide passing through the needle eye to the work, which comprises a detector element supported on the machine for reciprocatory movement in the direction of said run, said detector element having a thread engaging portion engaging and deflecting an intermediate portion of said run to form a transverse indent in said thread with the two legs thereof terminating respectively in said needle eye and in said thread guide, said detector element being biased in a direction to urge said thread engaging portion toward one end of said run, the tightening of the thread in high-speed repetition in said run with each needle reciprocation nudging said detector element including said thread engaging portion against said bias to maintain a position of said thread engaging portion in which the two legs of said indent are of nearly equal length, and a machine stop device comprising an electrical switch actuated by said movement of the detector element against said bias, and a solenoid actuated by said switch to stop the machine.

3. A sewing machine stop motion for use in a high speed sewing machine having sewing mechanism including a reciprocating eye-pointed needle operative in highspeed repetitive cycles, and thread guiding means including a thread take-up having a thread guide located to provide a direct run of the needle thread in a generally up and down direction from said thread guide passing through the needle eye to the work, which comprises a detector arm pivotally mounted on said machine, a thread engaging element on said detector arm movable in a path generally parallel to said run and engaging and deflecting an intermediate portion of the thread forming said run to form a transverse indent in said thread with the two legs thereof terminating respectively in said needle eye and in said thread guide, said arm being biased in a direction to urge said thread engaging element toward one end of said run, whereby the rapid tightening and loosening of said run of thread with each needle reciprocation nudges said detector arm and thread engaging element toward an intermediate machine running position in which said two legs of said indent are of nearly equal length, and a machine stop device arranged to be actuated by the biased movement of said detector arm and thread engaging element toward one end of said run from said machine running position.

4. A sewing machine stop motion for use in an automatic sewing machine according to claim 1 having a sewing mechanism and a work support relatively movable for sewing successive disconnected groups of stitches in a recurring automatic sequence of continuous machine operation, said stop motion comprising a stop motion actuating element actuated by a movement of said detector arm to said end of the run stop position, and means for rendering said needle thread actuated stop motion inoperative at a predetermined position in the automatic sequence of said work support, which comprises a control member mounted on said work support for movement therewith into restraining engagement with said thread detector arm for said predetermined position of said work support in said automatic sequence.

5. A sewing machine stop motion for use in an automatic sewing machine according to claim 1 having a sewing mechanism and a work support relatively movable for sewing successive disconnected groups of stitches in a recurring automatic sequence of continuous machine operation, said stop motion comprising a machine stop electrical circuit including a switch actuated by a movement of said detector arm to said end of the run stop position, and means for rendering said machine stop electrical circuit inoperative at a predetermined position in the automatic sequence of said work support, which comprises a cammed control arm on the machine shiftable between electrical circuit operative and inoperative positions, and a control member mounted on said work support for movement therewith adapted to engage and support said control arm in said circuit inoperative position for said predetermined position of said work support.

6. A sewing machine stop motion for use in an automatic sewing machine having a sewing mechanism and a work support movable relatively to the sewing mechanism for sewing successive disconnected groups of stitches in a recurring automatic sequence of continuous machine operation, said sewing mechanism including a reciprocating needle, and thread guiding means including a thread take-up, and a thread guide at the needle side of the thread take-up from which the thread is guided in a direct run to the needle eye in a generally up and down direction, which comprises a thread actuated machine stop assembly including a detector arm pivoted on the machine, a thread engaging element on said detector arm engaging and deflecting an intermediate portion of said run to form a transverse indent in said thread with the two legs thereof terminating respectively in said needle eye and in said thread guide, said arm being biased in a direction, to urge said thread engaging element toward one end of said run the tightening of the thread in said run with each needle reciprocation nudging said detector arm and thread engaging element toward an intermediate machine running position in which the two legs of said indent are of nearly equal length, a machine stop device comprising an electrical switch actuated by said biased movement of the detector arm toward one end of said run, and a solenoid actuated by said switch to stop the machine, and a device for rendering said thread actuated machine stop assembly inoperative including a control member mounted on said work support for movement therewith adapted for a predetermined position of the work support relative to the sewing mechanism to render said machine stop assembly inoperative to stop the machine.

7. A sewing machine stop motion for use in a high speed sewing machine having a sewing mechanism including a reciprocating eye needle and a thread guide from which the thread is guided in a direct run to the needle eye, and a work support relatively movable on said machine for sewing disconnected groups of stitches in a recurring automatic cycle, which comprises a thread controlled switch consisting of a contact arm engaging the sewing thread held open by the tension of said thread and adapted to be closed when the tension of said thread is released, a secondary switch connected in series with said thread controlled switch, means controlled by the relative movements of said sewing mechanism and work support for closing said secondary switch subsequent to the sewing of the first of a disconnected group of stitches, and an electrical stop circuit for said machine including said switches, and a machine stop element in series with said switches adapted to be energized by the closing of both said switches.

8. A sewing machine stop motion for use in a high speed sewing machine having sewing devices including a reciprocating eye needle, a work engaging element moving with the work, means for guiding the thread to the needle, and means to effect relative feeding movements of the work including said work engaging element and sewing devices for the insertion of a line of stitches, a thread controlled switch comprising a detector arm engaging said thread passing from said take-up device to the needle and held open by the tension of said thread, means whereby said arm closes said switch when the tension of said thread is released, cooperating cam and follower elements supported for movement respectively with said work engaging element and said sewing devices, a secondary switch connected with said follower controlled by said relative feeding movements to open during the sewing of at least a first stitch, and thereafter to close, and an electrical stop circuit for said machine including said switches in series, and a machine stop element energized by the closing of both said switches.

9. In a sewing machine adapted for automatic operation for the insertion of a row of stitches in accordance with a repetitive cycle having sewing mechanism including a reciprocating needle and a thread take-up device, and work feeding devices including a cross slide on which the work is supported having a limited lateral and return movement for the insertion of a line of stitches across the work, and means for advancing the work on the cross slide, the combination of a thread actuated stop motion for the machine comprising an electrical circuit including a solenoid and a machine stop element actuated by said solenoid, a thread detector arm responsive to a slack condition of said thread, and a switch in said circuit adapted to be closed by said response, a secondary switch in said circuit, and a cam and follower connection between said switch and said slide actuated by movement of said slide to open the switch during the sewing of at least a first stitch, and thereafter to close.

10. A sewing machine stop motion for use in an automatic sewing machine having a sewing mechanism and a work support relatively movable for sewing successive disconnected groups of stitches in a recurring automatic sequence of continuous machine operation, said sewing mechanism including a reciprocating needle, and thread guiding means including a thread take-up from which the thread is guided in a direct run to the needle eye, which comprises a thread actuated machine stop assembly including a thread detector element movably mounted on the machine for reciprocatory movement in the direction of said run, said detector element engaging and deflecting an intermediate portion of said run to form a transverse indent in said thread with the two legs thereof terminating respectively in said needle eye and said thread take-up, said detector element being biased in a direction to urge said thread engaging portion toward one end of said run and adapted to be supported in running position by said run of thread extending between the needle eye and thread take-up, and movable upon loss of said tension to a machine stop position, a stop motion actuating element actuated by a movement of said detector element to said stop position, and means for rendering said needle thread actuated stop motion inoperative at a predetermined position in the automatic sequence of said work support, which comprises a control member mounted on said work support for movement therewith, adapted for said predetermined position of the Work support to act upon said assembly in a manner to render said machine stop assembly inoperative.

References Cited in the file of this patent UNITED STATES PATENTS Weis Feb. 1, Thomas Mar. 28, Gahlert et a1. J an. 7, Moser Aug. 5, Morck Sept. 16, Vossen Oct. 23,

FOREIGN PATENTS Great Britain Nov. 5, 

1. A SEWING MACHINE STOP MOTION FOR USE IN A HIGH SPEED SEWING MACHINE HAVING SEWING MECHANISM INCLUDING A RECIPROCATING EYE-POINTED NEEDLE OPERATIVE IN HIGHSPEED REPETITIVE CYCLES, AND THREAD GUIDING MEANS INCLUDING A THREAD TAKE-UP HAVING A THREAD GUIDE LOCATED TO PROVIDE A DIRECT RUN OF THE NEEDLE THREAD FROM SAID THREAD GUIDE PASSING THROUGH THE NEEDLE EYE TO THE WORK, WHICH COMPRISES A DETECTOR ARM PIVOTALLY MOUNTED ON SAID MACHINE TO MOVE GENERALLY IN THE DIRECTION OF SAID RUN, A THREAD ENGAGING ELEMENT ON SAID DETECTOR ARM ENGAGING AND DEFLECTING AN INTERMEDIATE PORTION OF SAID RUN TO FORM A TRANSVERSE INDENT IN SAID THREAD WITH THE TWO LEGS THEREOF TERMINATING RESPECTIVELY IN SAID NEEDLE EYE AND IN SAID THREAD GUIDE, SAID ARM BEING BIASED IN A DIRECTION TO URGE SAID THREAD ENGAGING ELEMENT TOWARD ONE END OF SAID RUN, WHEREBY THE INTERMITTENT TIGHTENING OF SAID RUN OF THREAD IN HIGH-SPEED REPETTION WITH EACH NEEDLE RECIPROCATION NUDGES SAID THREAD ENGAGING ELEMENT AND DETECTOR ARM TO AN INTERMEDIATE RUNNING POSITION TENDING TOWARD THAT IN WHICH THE LEGS OF SAID INDENT ARE OF EQUAL LENGTH, AND A MACHINE STOP DEVICE ARRANGED TO BE ACTUATED BY THE BIASED MOVEMENT OF SAID DETECTOR ARM AND THREAD ENGAGING ELEMENT TOWARD ONE END OF SAID RUN FROM SAID MACHINE RUNNING POSITION. 